Note 5 - Loans and Allowance for Loan Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016		Dec. 31, 2016
Balance, beginning of period					$ 36,286,000
Provision for loan losses	$ 5,462,000		$ 8,294,000		16,792,000		$ 15,733,000
Balance, end of period	42,717,000				42,717,000
Loans, Excluding Acquired Loans [Member]
Balance, beginning of period	41,379,000	[1]	33,523,000	[2]	36,286,000	[3]	31,351,000	[2]
Provision for loan losses	5,462,000	[4]	8,079,000	[5]	15,327,000	[4]	15,211,000	[5]
Charge-offs	(5,174,000)		(7,880,000)		(12,295,000)		(14,135,000)
Recoveries	1,050,000		372,000		3,399,000		1,667,000
Net charge-offs	(4,124,000)		(7,508,000)		(8,896,000)		(12,468,000)
Balance, end of period	42,717,000	[1]	34,094,000	[2]	42,717,000	[1]	34,094,000	[2]
Loans individually evaluated for impairment	6,321,000		580,000		6,321,000		580,000		$ 680,000
Loans collectively evaluated for impairment	36,396,000		33,514,000		36,396,000		33,514,000		35,606,000
Loans, Excluding Acquired Loans [Member] | Commercial Portfolio Segment [Member]
Balance, beginning of period	8,105,000	[1]	7,832,000	[2]	7,739,000	[3]	5,985,000	[2]
Provision for loan losses	2,310,000	[4]	680,000	[5]	3,255,000	[4]	4,961,000	[5]
Charge-offs	(2,442,000)		(284,000)		(3,083,000)		(3,043,000)
Recoveries	21,000		12,000		83,000		337,000
Net charge-offs	(2,421,000)		(272,000)		(3,000,000)		(2,706,000)
Balance, end of period	7,994,000	[1]	8,240,000	[2]	7,994,000	[1]	8,240,000	[2]
Loans individually evaluated for impairment	3,996,000		64,000		3,996,000		64,000		262,000
Loans collectively evaluated for impairment	3,998,000		8,176,000		3,998,000		8,176,000		7,477,000
Loans, Excluding Acquired Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, beginning of period	25,731,000	[1]	19,635,000	[2]	21,817,000	[3]	19,522,000	[2]
Provision for loan losses	2,150,000	[4]	6,066,000	[5]	7,984,000	[4]	7,009,000	[5]
Charge-offs	(896,000)		(6,297,000)		(3,264,000)		(7,350,000)
Recoveries	309,000		55,000		757,000		278,000
Net charge-offs	(587,000)		(6,242,000)		(2,507,000)		(7,072,000)
Balance, end of period	27,294,000	[1]	19,459,000	[2]	27,294,000	[1]	19,459,000	[2]
Loans individually evaluated for impairment	2,325,000		515,000		2,325,000		515,000		417,000
Loans collectively evaluated for impairment	24,969,000		18,944,000		24,969,000		18,944,000		21,400,000
Loans, Excluding Acquired Loans [Member] | Consumer Portfolio Segment [Member]
Balance, beginning of period	3,754,000	[1]	3,748,000	[2]	3,779,000	[3]	3,893,000	[2]
Provision for loan losses	761,000	[4]	501,000	[5]	2,168,000	[4]	1,422,000	[5]
Charge-offs	(1,017,000)		(699,000)		(2,962,000)		(2,260,000)
Recoveries	275,000		199,000		788,000		694,000
Net charge-offs	(742,000)		(500,000)		(2,174,000)		(1,566,000)
Balance, end of period	3,773,000	[1]	3,749,000	[2]	3,773,000	[1]	3,749,000	[2]
Loans individually evaluated for impairment
Loans collectively evaluated for impairment	3,773,000		3,749,000		3,773,000		3,749,000		3,779,000
Loans, Excluding Acquired Loans [Member] | Unallocated Financing Receivables [Member]
Balance, beginning of period	3,789,000	[1]	2,308,000	[2]	2,951,000	[3]	1,951,000	[2]
Provision for loan losses	241,000	[4]	832,000	[5]	1,920,000	[4]	1,819,000	[5]
Charge-offs	(819,000)		(600,000)		(2,986,000)		(1,482,000)
Recoveries	445,000		106,000		1,771,000		358,000
Net charge-offs	(374,000)		(494,000)		(1,215,000)		(1,124,000)
Balance, end of period	3,656,000	[1]	2,646,000	[2]	3,656,000	[1]	2,646,000	[2]
Loans individually evaluated for impairment			1,000				1,000		1,000
Loans collectively evaluated for impairment	$ 3,656,000		$ 2,645,000		$ 3,656,000		$ 2,645,000		$ 2,950,000

[1] Allowance for loan losses at September 30, 2017 includes $391,000 allowance for loans acquired (not shown in the table above). Allowance for loan losses at December 31, 2016 includes $954,000 allowance for loans acquired. The total allowance for loan losses at September 30, 2017, June 30, 2017 and December 31, 2016 was $43,108,000, $41,770,000 and $37,240,000, respectively.

[2] Allowance for loan losses at September 30, 2016, June 30, 2016 and December 31, 2015 includes $954,000 allowance for loans acquired. The total allowance for loan losses at September 30, 2016, June 30, 2016 and December 31, 2015 was $35,048,000, $34,477,000 and $32,305,000, respectively.

[3] Allowance for loan losses at December 31, 2016 includes $954,000 allowance for loans acquired (not shown in the table above). The total allowance for loan losses December 31, 2016 was $37,240,000.

[4] Provision for loan losses of $1,464,000 attributable to loans acquired was excluded from this table for the nine months ended September 30, 2017 (total provision for loan losses for the three and nine months ended September 30, 2017 was $5,462,000 and $16,792,000). There was $2.0 million in charge-offs for loans acquired during the nine months ended September 30, 2017 resulting in an ending balance in the allowance related to loans acquired of $391,000.

[5] Provision for loan losses of $215,000 and $522,000 attributable to loans acquired was excluded from this table for the three and nine months ended September 30, 2016 (total provision for loan losses for the three and nine months ended September 30, 2016 was $8,294,000 and $15,733,000). The $215,000 and $522,000 was subsequently charged-off, resulting in no change in the ending balance in the allowance related to loans acquired.